The present invention relates generally to improvements in position sensing devices and it relates more particularly to an improved system for sensing the closed position of a door, window or other closure member.
In burglar alarm systems it is a common practice to provide switches at windows and doors in a manner that the switch is transferred between its open and close state with the opening and closing of the door and the state of the switch controls an alarm or the transmission of an information signal to a remote monitoring point. The switches are generally mechanical in nature and usually include a pair of switch contacts which are shorted by a conductor strip carried by the window or door and when in closed position. The use of mechanical switches in sensing the position of a closure member possesses numerous drawbacks and disadvantages. They are easily by-passed and tampered with to provide a closure member closed response even when such closure member is in a fully open position, they are unreliable and easily disabled devices, are of limited versatility and adaptability and otherwise leave much to be desired. The use of permanent magnet actuated switches have been employed but this has not remedied the deficiencies and drawbacks of the mechanically operated switches.